Python Data Driven framework for acceleration of Phase-Field simulations[Formula presented]

peer reviewedThe passage describes the development of a numerical framework in Python to create and process a large dataset for time-series prediction using Deep Learning algorithms. The dataset is generated by solving the Cahn–Hilliard equation for spinodal decomposition of a binary alloy and is labeled to train the algorithms. Prior to training, dimensionality reduction is performed using Auto-encoders and Principal Component Analysis. The framework identifies three distinct latent dimensions/spaces for the datasets. The primary dataset was generated by running up to 10,000 High-Fidelity Phase-Field simulations in parallel using High-Performance Computing (HPC). The framework is compatible with all major operating systems and has been thoroughly tested on Python 3.7 and later versions

About the use of Phase Field and FE to predict micostructures, Application on AlSi10Mg samples produced by Additive Manufacturing

Background & motivations Finite Element (FE) model in Additive Manufacturing (AM) AlSi10Mg Microstructure evolution FE Model of L-PBF (SLM) AlSi10Mg Phase-field model of microstructure evolution: Model description Model parameters Simulated calorimetric curve Conclusion

Adaptive time stepping approach for Phase-Field modeling of phase separation and precipitates coarsening in additive manufacturing alloys

In the present work, the capacity of phase field method to highlight microstructural changes during the spinodal decomposition of a given binary alloy basing on the Cahn-Hilliard equation is presented. Then, growth and coarsening of precipitates are studied using the KKS (Kim-Kim-Suzuki) model, which includes Cahn-Hilliard and Allen-Cahn equations. The implementation of time stepping algorithms to resolve Phase-Field equations is illustrated. Within Fourier space, using semi-implicit spectral method, it has been demonstrated that it allows faster computing than schemes based on finite difference method. First, spinodal decomposition of a given binary alloy under isothermal loading is implemented and three time stepping approaches are applied: constant time stepping, non- iterative and an iterative method. While the non-iterative method is faster than the constant time stepping scheme, the iterative one, although relatively more CPU consuming, can guarantee the convergence of the computing. These methods are combined in an innovative approach tested on 1D, 2D and 3D grids. The effectiveness of the adopted adaptive time-stepping algorithm allows resolving equations in reasonable CPU time. It predicts different physical phenomena, such as phase separation and growth and coarsening of precipitates induced by important interfacial energies

Microstructure and properties of SLM AlSi10Mg: Understanding the influence of the local thermal history

peer reviewedSelective Laser Melting (SLM) is an Additive Manufacturing technique that is widely used to produce AlSi10Mg parts with a good strength-to-weight ratio. Indeed, strongly refined microstructures are obtained due to the ultra-fast cooling rates reached in this process, conferring high strength to the parts, even in the as-built state. However, microstructural heterogeneities at the scale of the melt pool may exert a detrimental influence on the mechanical properties e.g. by causing a loss in ductility. This study thus aims at a better understanding of the influence of the local thermal history on local variations of microstructure and mechanical properties. Microscopy (i.e. SEM+EDS) and nanoindentation have been combined to reach a detailed knowledge of the local microstructure and properties. In particular, the solute Si content in the -Al matrix, the volume fraction and the size of Si precipitates have been quantified by microscopy analysis. These local microstructural parameters are correlated with the matrix hardness as revealed by nanoindentation. Finally, the results of this detailed characterization are linked with the local thermal history that is approached in two different ways i.e. (i) an analytical description of thermal gradients inside the melt pool based on Rosenthal’s and Matyja’s equations and (ii) a simple Finite Element model for the deposition of a few layers in the SLM process

Prediction of static properties of LPBFAlSi10Mg samples post-treated by Friction Stir Processing or thermal treatments

peer reviewedLongLifeA

Controlled precipitation in a new Al-Mg-Sc alloy for enhanced corrosion behavior while maintaining the mechanical performance

peer reviewedThe hot working of 5xxx series alloys with Mg ≥3.5 wt% is a concern due to the precipitation of β (Al3Mg2) phase at grain boundaries favoring Inter Granular Corrosion (IGC). The mechanical and corrosion properties of a new 5028-H116 Al-Mg-Sc alloy under various β precipitates distribution is analyzed by imposing different cooling rates from the hot forming temperature (i.e. 325 °C). The mechanical properties are maintained regardless of the heat treatment. However, the different nucleation sites and volume fractions of β precipitates for different cooling rates critically affect IGC. Controlled furnace cooling after the 325 °C heat treatment is ideal in 5028-H116 alloy to reduce susceptibility to IGC after sensitization

Microstructure prediction in additive manufacturing(TA6V, AlSi10Mg, AISI M4 materials)

Bilan des travaux depuis 3 ans sur 3 matériaux en additive manufacturin

How to feed and validate a phase-field model predicting the evolution of microstructures and properties in AlSi10Mg processed by Selective Laser Melting

AlSi10Mg processed by Selective Laser Melting (SLM) exhibits an out-AlSi10Mg processed by Selective Laser Melting (SLM) exhibits an out-of-equilibrium microstructure as a result of rapid solidification. This microstructure is composed of α-Al sub-micron cells surrounded by an eutec- tic mixture of Si precipitates in an Al matrix. The rapid solidification also results in an extended Si solute content in solid solution inside the Al cells. The Si atoms in solid solution and the fine Si precipitates both contribute to the high strength and the thermo-physical properties of AlSi10Mg SLM, particularly its low thermal conductivity. Moreover, the microstructure and its associated properties is process parameter dependent. The microstructure is deeply affected when submitted to a thermal field. This can happen either (i) locally due to the heat input accompanying the deposition of a new layer or (ii) in the bulk by the effect of build platform temperature or (iii) during post-treatments. At low temper- ature, the Si in solid solution tends to precipitate out in the α-Al cells while at intermediate or high temperature, the pre-existing Si precipitates in the eutectic coarsen. As a result, the strength and the thermo-physical properties of the alloy are modified. The present thesis thus aims to investigate the impact of these process parameters on the mi- crostructure evolution and the related tensile and thermo-physical properties of AlSi10Mg SLM. In a first step, microstructural characterizations and tensile tests are performed to study the in- fluence of the laser power, scan speed and the build platform temperature. From the collected data, the preferential rupture zone in tension is identified and a hardening model connecting microstructure and tensile properties is developed. Then thermal models of the SLM process validated against experiments and able to reproduce the as-built microstructure are used to ex- tract the thermal history in the preferential rupture zone. Thermo-physical properties are needed as inputs in the models. During their measurements, the microstructure undergoes transforma- tions which affect in return the measured thermo-physical properties. To address the device limi- tation, the non-equilibrium thermo-physical properties of AlSi10Mg SLM are calculated through a CALculation of PHase Diagram (CALPHAD) model. Finally, a phase-field model tracking the nucleation, growth and coarsening kinetics of Si precipitates is developed and validated against experiment. The model investigates the effect of build platform temperature on the microstruc- ture evolution of AlSi10Mg SLM. This Phd work developed a framework to predict the microstructure evolution and asso- ciated tensile and thermo-physical properties of AlSi10Mg SLM submitted to any process or post-process conditions.L’AlSi10Mg produit par fusion sélective par laser (SLM) présente une microstructure hors d’équilibre en raison de la solidification rapide. Cette microstructure est composée de cellules submicroniques d’Al-α entourées d’un mélange eutectique de précipités de Si dans une matrice en Al. La solidification rapide induit également une teneur étendue de Si en solution solide à l’intérieur des cellules d’Al. Les atomes de Si en solution solide ainsi que les fins précipités de Si contribuent à la résistance élevée et aux propriétés thermophysiques du AlSi10Mg SLM, notam- ment sa faible conductivité thermique. De plus, la microstructure et les propriétés qui lui sont associées dépendent des paramètres de fabrication. La microstructure est profondément affectée lorsqu’elle est soumise à un champ thermique. Cela peut se produire soit (i) localement en raison de l’apport de chaleur accompagnant le dépôt d’une nouvelle couche, soit (ii) dans la masse par l’effet de la température du plateau de fabrica- tion, soit (iii) lors de post-traitements. À basse température, le Si en solution solide a tendance à précipiter dans les cellules d’ Al-α tandis qu’à température intermédiaire ou élevée, les précipités de Si préexistants dans l’eutectique grossissent. En conséquence, la résistance et les propriétés thermo-physiques de l’alliage s’en trouvent modifiées. La présente thèse a donc pour but d’étudier l’impact de ces paramètres procédé sur l’évolution de la microstructure et les propriétés de traction et thermophysiques associées de l’AlSi10Mg SLM. Dans un premier temps, des caractérisations microstructurales et des essais de traction sont réalisés pour étudier l’influence de la puissance du laser, de la vitesse de balayage et de la température du plateau de fabrication. À partir des données recueillies, la zone de rupture préférentielle en traction est identifiée et un modèle de durcissement reliant la microstructure et les propriétés en traction est développé. Ensuite, des modèles thermiques du procédé SLM validés par des expériences et capables de reproduire la microstructure brute de fabrication sont utilisés pour extraire l’histoire thermique dans la zone de rupture préférentielle. Les propriétés thermo-physiques sont nécessaires comme entrées dans ces modèles. Pendant leurs mesures, la microstructure subit des transformations qui affectent en retour les propriétés thermophysiques mesurées. Pour répondre à la limitation du dispositif expérimental, les propriétés thermo- physiques hors équilibre du AlSi10Mg SLM sont calculées à l’aide d’un modèle CALPHAD (calcul des diagrammes de phase). Enfin, un modèle de champ de phase suivant la cinétique de nucléation, de croissance et de grossissement des précipités de Si est développé et validé par rapport à l’expérience. Le modèle étudie l’effet de la température de la plateforme de fabrication sur l’évolution de la microstructure du AlSi10Mg SLM. Ce travail de thèse a permis de développer un cadre pour prédire l’évolution de la mi- crostructure et les propriétés thermophysiques et de traction associées du AlSi10Mg SLM soumis à n’importe quelle condition de fabrication ou post-fabrication

Investigation of out-of-equilibrium thermo-physical properties of AlSi10Mg processed by LPBF through modeling and experiment

peer reviewedThe AlSi10Mg processed by the additive manufacturing Laser Powder Bed Fusion (LPBF) exhibits an out of-equilibrium microstructure as a result of rapid solidification inside the melt pool. During the measurement of the thermo-physical properties, the as-built microstructure undergoes a transformation at high temperature accompanying by a change of properties. To address the device limitation over this temperature range, the thermo-physical properties of the as-built AlSi10Mg is investigated through a CALPHAD (CALculation of Phase Diagram) model associated to a non-equilibrium solidification model. The computed thermo-physical properties is in agreement with the experimental one at low temperature where the as-built microstructure is conserved while the models provide extrapolated values at high temperature. The corresponding thermo-physical data can be used as inputs for models of the LPBF process

2D FE Modeling of the Thermal History of the Heat Affected Zone in AlSi10Mg LPBF

peer reviewedAs an easily processable Al alloy, AlSi10Mg manufactured by Laser Powder Bed Fusion (LPBF) has received a lot of attention so far. However, it is well known that microstructural heterogeneities at the scale of the melt pool – in particular the weaker Heat Affected Zone whose microstructure evolves during the deposition of the next layer – exert a strong detrimental effect on the ductility of AlSi10Mg LPBF. In this work, a 2D Finite Element (FE) model is developed in order to tackle this issue and help in guiding the optimisation of LPBF process parameters. The model is calibrated using experimental measurements of the melt pool height. Furthermore, to allow for the efficient simulation of 5 successive layers, a remeshing procedure is implemented. No heat accumulation is observed during the deposition of these 5 layers. The thermal history of the HAZ can thus be studied with a thermal model for one layer.LonglifeAMIawath